Among bone cell metabolic pathways in which tryptophan is involved, Lemonnier et al., 2000 [19], have demonstrated that in Apert Syndrome, a form of acrocephalosyndactyly characterized by premature ossification and fusion of cranial sutures, the origin of the pathology is the Ser252Trp mutation of the fibroblast growth factor receptor FGFR2. This evidence concerns the gene FGFR2 and Apert syndrome.